title: EMT defibrillation does not increase survival from sudden cardiac death in a two-tiered urban-suburban EMS system.
abstract: OBJECTIVE
  The use of automatic external defibrillators (AEDs) by EMS initial responders is widely advocated. Evidence supporting the use of AEDs is based largely on the experience of one metropolitan area, with effect on survival in many systems not yet proved. We conducted this study to determine whether the addition of AEDs to an EMS system with a response time of 4 minutes for first-responder emergency medical technicians (FREMTs) and 10 minutes for paramedics would affect survival from cardiac arrest.
  
  
  METHODS
  This prospective, controlled, crossover study (AED versus no AED) of consecutive cardiac arrests managed by 24 FREMT fire companies took place from 1992 to 1995 in Charlotte, North Carolina, a city of 455,000. Patients were stratified using the Utstein criteria. The primary endpoint was survival to hospital discharge among patients with bystander-witnessed arrests of cardiac origin.
  
  
  RESULTS
  Of the 627 patients, 243 were bystander-witnessed arrests of cardiac origin. Survival to hospital discharge was accomplished in 5 of 110 patients (4.6%; 95% confidence interval [CI] 0.6% to 8.4%) with AED compared with 7 of 133 (5.3%, 95% CI 1.5% to 9.1%) without AED (P = .8). Both groups were comparable with regard to age, gender, history of myocardial infarction, congestive heart failure or diabetes, arrest at home, bystander CPR, and whether or not ventricular fibrillation (VF) was the initial rhythm. For arrests of any cause, witnessed by bystanders or EMS personnel, with an initial rhythm of VF or ventricular tachycardia (VT), 5 of 77 (6.5%, 95% CI 1.0% to 12.0%) with AED survived compared with 8 of 105 patients (7.6%, 95% CI 2.5% to 12.7%) without AED (P = .8). Statistically significant differences were noted in race and EMS response times between the two groups, which did not affect survival.
  
  
  CONCLUSIONS
  Addition of AEDs to this EMS system did not improve survival from sudden cardiac death. The data do not support routinely equipping initial responders with AEDs as an isolated enhancement, and raise further doubt about such expenditures in similar EMS systems without first optimizing bystander CPR and EMS dispatching.
authors.affiliation: Department of Emergency Medicine, Medical Center of Delaware, Wilmington, USA. TSweeney@christianacare.org
authors.forename: T A
authors.initials: TA
authors.lastname: Sweeney
authors.forename: J W
authors.initials: JW
authors.lastname: Runge
authors.forename: M A
authors.initials: MA
authors.lastname: Gibbs
authors.forename: J M
authors.initials: JM
authors.lastname: Raymond
authors.forename: R W
authors.initials: RW
authors.lastname: Schafermeyer
authors.forename: H J
authors.initials: HJ
authors.lastname: Norton
authors.forename: M J
authors.initials: MJ
authors.lastname: Boyle-Whitesel
mesh_terms: D000368:Aged; D016887:Cardiopulmonary Resuscitation; D018592:Cross-Over Studies; D016757:Death, Sudden, Cardiac / Q000517:prevention & control*; D004554:Electric Countershock; D004631:Emergency Medical Service Communication Systems; D004632:Emergency Medical Services / Q000706:statistics & numerical data*; D005260:Female; D006323:Heart Arrest / Q000401:mortality / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011446:Prospective Studies; D019036:Suburban Health Services; D016019:Survival Analysis; D019037:Urban Health Services